The present invention pertains to an emergency power supply system and method for operating freight loading dock equipment, such as dock levelers and truck restraint devices, utilizing electrical power from electric lift trucks and the like.
Freight loading docks for motor trucks employ a substantial amount of electric powered equipment, including dock levelers or dockboards and truck restraints, for example. In freight loading docks for large warehouses, production facilities and freight carrier freighthouses, a substantial number of electric powered dock levelers and truck restraints may be operated on a substantially around the clock basis. Certain types dock levelers use electric motor powered hydraulic operating mechanisms. Examples of such dock levelers are commercially available from the assignee of the present invention through its W.B. McGuire Company. For example, W.B. McGuire MKA series and AUTODOK series dock levelers use electric motor powered hydraulic pumps to raise and lower the dock leveler ramps. Certain types of dock levelers are all electric powered, such as the type disclosed and claimed in U.S. Pat. No. 6,163,913, also assigned to the assignee of the present invention. Still further, freight loading docks may utilize electric motor powered truck restraints associated with each dock station.
The above-mentioned dock equipment is normally wired for use of electric utility supplied power via conventional power distribution networks and through conventional voltage stepdown transformers to supply power at relatively low AC voltages, for example. This reliance on utility supplied power can, of course, create certain problems in operating large freight loading docks which are in use in around the clock warehouse operations and freight carrier freighthouses, as well as large commercial production manufacturing and distribution facilities. In this regard it has been deemed highly desirable and often necessary to consider providing an emergency power supply in the event of loss of utility supplied electrical power.
Freight loading docks also, in most instances, utilize several electric motor powered hand and rider type freight moving vehicles for use in loading and unloading larger over the road freight hauling trucks, such freight moving vehicles including those commonly known as forklift trucks. Electric motor powered rider and hand operated type lift trucks typically carry an onboard power supply, such as a storage battery bank, providing relatively low voltage direct current (DC) power, such as twelve volt DC to fortyeight volt DC power, for example. Since such lift trucks can serve as a source of electric power, it would be advantageous to utilize them for providing emergency power to operate dock equipment, such as dock levelers, dockboards and truck restraints. It is to these ends that the present invention has been developed.
The present invention provides an emergency power supply system and method for operating freight loading dock equipment, such as electric motor powered dock levelers, dockboards and truck restraints, for example.
In accordance with one aspect of the present invention an emergency power supply system is provided for operating a dock leveler using a lift truck as a power supply source, such as a battery bank onboard the lift truck. The emergency power supply system includes a power cable for connecting the onboard battery bank of the lift truck to a controller for a dock leveler, for example. A flexible power cable assembly may be interconnected between the lift truck and a control circuit included in the dock equipment controller. The controller includes circuitry which is operable to be switched from using utility supplied power to using power from a lift truck battery bank. The controller includes a connector plug for connecting the flexible power cable assembly to the controller, a selector switch for selecting the power source to be from the utility supplied power or the lift truck supplied power, as the case may require. Still further, the controller may utilize a transformer and rectifier for converting high voltage utility supplied alternating current (AC) power to the proper direct current (DC) voltage required of the dock equipment motor and which is compatible with the voltage of the lift truck battery bank.
In accordance with another aspect of the invention a method is provided for operating freight loading dock equipment on an emergency basis which includes the steps of providing a controller for the dock equipment which is operably connected to the dock equipment electric motor, the controller including a selector switch and, when a loss of utility supplied power is incurred, an electric powered freight moving vehicle or lift truck is parked in the vicinity of the controller, a quick connect/disconnect electric cable assembly is interconnected between the lift truck onboard battery bank and the controller and the selector switch on the controller is positioned to provide for supply of electric power to the dock equipment from the lift truck. The dock equipment may then be operated on an emergency basis to move between an operating position and a stored or so-called cross traffic position, in the case of a dock leveler, and to move a truck restraint between a working position and a stored position, as needed. In this way freight loading docks may utilize an alternate or emergency power source which is convenient, readily available under virtually all operating circumstances, and may be used on an emergency basis to operate dock equipment to provide for loading, unloading and moving freight vehicles with respect to the dock facility at the which the dock equipment is disposed.
Those skilled in the art will further appreciate the above described advantages and superior features of the invention, together with other important aspects thereof upon reading the detailed description which follows in conjunction with the drawings.